DE102006014836A1 - Electro-hydraulic braking system for motor vehicle, has seat valves that are upstream of brake assemblies and acting as inlet valve in both push through and brake by wire modes for supplying brake assemblies with fluid - Google Patents

Abstract

The system has an energy device (100) and a brake pedal device (201) for supplying hydraulic fluid in a brake by wire mode and a push through mode of an electro-hydraulic braking system, respectively. Brake assemblies (203, 205, 207, 209) are coupled with a vehicle wheel, and are fluidically connected with the energy and brake pedal devices. Electromagnetically actuated seat valves (306a-306d) are upstream of the brake assemblies, and act as an inlet valve in both push through and brake by wire modes for supplying the brake assemblies with the fluid.

Description

Territory of invention

The The invention relates to an electro-hydraulic brake system for motor vehicles, with a first means for providing pressurized Hydraulic fluid in a "brake-by-wire" operation and a second means for providing pressurized Hydraulic fluid in a "push-through" operation of the electro-hydraulic brake system and at least one coupled to at least one vehicle wheel Brake device associated with the first and second device in fluid connection can be brought.

background the invention

at an electrohydraulic brake system is the driver on Brake pedal detected by sensors and in the form of electrical Signals supplied to an electronic control, which is an electrical Activates brake pressure transducer. That's why such systems are too referred to as "brake-by-wire" systems. To the vehicle even in case of failure of the vehicle electrical system yet with a minimum delay to be able to slow down indicates the brake system additionally a redundant hydraulic emergency brake functionality, the directly and without any electronic control on the brakes the vehicle wheels acts.

at the hydraulic emergency brake functionality is in conventional Way over a fußkraftbetätigbaren Brake pressure transducer and hydraulic lines a direct connection produced between the brake pedal and the wheel brakes of the motor vehicle. This functionality is also referred to as "push-through" operation. To switch to brake-by-wire operation, it requires a switching device. The switching device provides sure that during normal operation the electrically generated brake pressure is transmitted to the wheel brakes.

An electro-hydraulic brake system of the type mentioned is, for example, from the DE 10 2004 016141 known. In the electro-hydraulic brake system described there is, as in 1 is shown, an electro-hydraulic power unit is provided, which is a hydraulic pump 102 and a pressure accumulator 104 having. Furthermore, brakes 203 . 205 . 207 . 209 and speed sensors 262 . 264 . 266 . 268 at the wheels 202 . 204 . 206 . 208 provided for measuring the rotational speeds of the wheels. The driver communicates his braking request to the system via a brake pedal 214 With. The pedal 214 is with a master cylinder 218 and a simulation piston 216 connected. The simulation piston 216 serves to give the driver the feel of a conventional brake pedal of a conventional hydraulic brake system.

The one from a battery 210 powered electrical control unit 212 receives measurement data from the pedal sensor X, which determines the traveled pedal travel and / or the operating speed, the sensor group 272 with the pressure sensors P1 to P7, the temperature sensors T1, T2, and the speed sensors 262 . 264 . 266 . 268 , The electronic control unit 212 determines from the provided parameters the deceleration request of the driver.

For braking, the driver operates the brake pedal 214 , Then the proportional valves 238 . 240 . 244 . 246 from the control unit 212 controlled, the fluid pressure from the accumulator 104 over the separating pistons 222 . 224 to the wheel brakes 207 . 209 hand off. The with the master cylinder 218 the brake pedal unit 201 connected control valves 230 . 232 stay closed. The actual brake pressures are detected by the pressure sensors P1, P2, P3, P4, P5 and returned to the electronic control unit 212 forwarded, creating a control loop.

Decreases after the braking of the pressure in the accumulator 104 below a certain value, becomes the hydraulic pump 102 turned on to the pressure accumulator 104 again to apply brake fluid. When a certain pressure is reached, the pump becomes 102 switched off again. Turning the pump on or off 102 happens through the control unit 212 ,

In order to release the brakes of the front and rear wheels, the proportional valves 236 . 242 . 243 . 248 opened and the proportional valves 238 . 240 . 244 . 246 closed. As a result, the pressure in the brake lines of the wheel brakes 203 . 205 . 207 . 209 drained. The balancing valves 239 . 250 can stay open. The brake fluid flows through the control valves 236 . 242 and back to the pressureless brake fluid reservoir 220 , With the return of the brake fluid to the brake fluid reservoir 220 this can then again the pressure chambers of the brake cylinder 218 fill with brake fluid.

Should there be problems with the pressure supply due to, for example, failure of the hydraulic pump 102 or failure of the pressure accumulator 104 A hydraulic brake circuit provides the necessary brake pressure at the wheel brakes. About the master cylinder 218 The driver can, as in a conventional hydraulic brake system, the braking purely mechanical about the foot force and the hydraulic ratio by the brake pedal 214 initiate. The hydraulic Pressure is thereby over the master brake cylinder 218 built and directly on the opened in the non-switching state control valves 230 . 232 to the wheel brakes 203 . 205 forwarded. Thus, in case of failure of the vehicle electrical system, the vehicle by pressing the brake pedal 214 be hydraulically braked ("push-through").

The in the 1 shown and described above electro-hydraulic brake system is complex and has a whole network of hydraulic fluid lines, which are provided in accordance with control valves, proportional valves, separating pistons, sensors, etc. Each individual component of this electro-hydraulic brake system contributes to the overall weight of the vehicle, which in turn has a lasting effect on the energy consumption of the motor vehicle. Furthermore, such complex design brake systems are expensive to manufacture, maintenance and assembly.

It is therefore an object of the present invention, a simplified provide electro-hydraulic brake system, the cheaper is to produce and fewer components, such as supply and supply lines, Control valves, proportional valves, separating piston, etc., but nevertheless, the safety standards imposed on such a brake system Fulfills.

Summary the invention

to solution The above object provides a first aspect of the invention an electro-hydraulic brake system with a first device for providing pressurized hydraulic fluid in a "brake-by-wire" operation and a second means for providing pressurized Hydraulic fluid in a "push-through" operation of the electrohydraulic Brake system and at least one with at least one vehicle wheel coupled braking device, with the first and the second Device in fluid communication can be brought. An electromagnetic actuated Control valve is connected upstream of the braking device, both in "push-through" as well as "brake-by-wire" operation as an inlet valve serves to pressurize the brake device with hydraulic fluid.

The the braking device upstream, electromagnetically actuated Control valve takes over in the electrohydraulic invention Brake system a dual function, as it is both in the "push-through" and "brake-by-wire" operation as an inlet valve serves. As a result, usually no further control valve is necessary for example, takes over the function of an intake valve in the "brake-by-wire" operation.

The Electromagnetically actuated Control valve can open in a non-conducting state, Electromagnetically actuated Be seat valve. The seat valve opened in the non-switching state can even in case of failure of the vehicle electrical a rapid hydraulic pressure build-up in the vehicle wheels ensure associated braking devices, bringing the electro-hydraulic Brake system to such safety standards in particular met in "push-through" operation.

Farther at least partially covers the electro-hydraulic brake system separate hydraulic fluid circuits for push-through and brake-by-wire operation. It can an electromagnetically actuated Control valve may be provided, these two hydraulic fluid circuits from each other decoupled or disconnected. This ensures that a certain Used part of the hydraulic fluid lines both for the "push-through" as well as for the "brake-by-wire" operation can be.

The Electromagnetically actuated Control valve, which is the "push-through" hydraulic fluid circuit from the "brake-by-wire" hydraulic fluid circuit separates, according to a development of the invention in a non-switching Condition opened valve be.

at a further embodiment of the electro-hydraulic brake system according to the invention a closed circuitless, electromagnetic actuated Control valve downstream of the braking device. This downstream Control valve serves as an exhaust valve and leaves the pressure reduction in the brake devices that Hydraulic fluid back to a hydraulic fluid reservoir.

A further embodiment of the electro-hydraulic brake system sees in that an output side of the first means for providing Under pressure, the hydraulic fluid is in "brake-by-wire" operation with a in the circuitless state closed, electromagnetically actuated Control valve is connected. This control valve, that in the uninterruptible Condition is closed, prevented in the "push-through" operation of the brake system penetration of hydraulic fluid in the first device, which in the "brake-by-wire" operation under pressure Hydraulic fluid provides. In particular, the "push-through" operation becomes faster Pressure build-up in the braking devices allows.

Furthermore, the control valve, which is connected to the output side of the first means for providing pressurized hydraulic fluid in "brake-by-wire" operation, may be an electromagnetically operable proportional valve the hydraulic fluid pressure provided by the first device tion moderately changed by the proportional valve.

at a development of the invention, the electro-hydraulic brake system for one 4-wheel "push-through" operation trained be.

Further may be an output side of the second device under pressure providing standing hydraulic fluid in "push-through" operation, with a braking device of a front wheel and a rear wheel be brought into fluid communication. This diagonal distribution of Ensures brake pressure on a front wheel and a rear wheel, that the vehicle is stable, especially when cornering or on slippery road surface, can be slowed down. Indicates the second facility to provide pressurized hydraulic fluid in "push-through" operation two pressure chambers each with an output side, can with insufficient pressure build-up in one of the pressure chambers, e.g. because of a leaking pressure chamber, always the braking device of a front wheel with hydraulic fluid is applied, resulting in an improved braking deceleration of the vehicle leads.

According to one Another aspect of the present invention may be an electromagnetic actuated Control valve upstream of the braking device, the "push-through" operation as an inlet valve is used to apply the braking device with the second Device provided hydraulic fluid, and in the "push-through" and "brake-by-wire" operation as an exhaust valve serves to drain hydraulic pressure from the brake device. Thus, the brake device upstream control valve take over three different functions. On the one hand, it serves as an inlet valve in push-through mode and on the other hand it serves as an outlet valve in "push-through" and "brake-by-wire" operation. As a result, the number of control valves is reduced, which at a in "push-through" and "brake-by-wire" operation fully functional electro-hydraulic Brake system must be present.

The Electromagnetically actuated Control valve can open in a non-conducting state, Electromagnetically actuated Proportional valve. The proportional valve ensures in particular during pressure build-up a control change of the hydraulic fluid pressure, with which the braking devices are acted upon.

Of Furthermore, the electro-hydraulic brake system for a 4-wheel "push-through" operation trained be, each braking device is an electromagnetically actuated Control valve is connected upstream. A 4-wheel "push-through" capable electrohydraulic Brake system improves the minimum deceleration of the vehicle in case of failure the vehicle electrics. By doing that every single braking device a control valve can be connected upstream, any braking device individually acted upon with hydraulic fluid and thus targeted to Initiate a braking operation to be actuated.

at the electro-hydraulic brake system, one of the braking device associated "brake-by-wire" hydraulic circuit be provided, the one the first means of deployment hydraulic fluid pressure comprising the first section and the one Braking device comprising the second section, wherein the first section separated from the second section by a check valve is. The check valve prevents for example the penetration of gas bubbles or impurities from the field of wheel brakes in the first device comprehensive Section of the "brake-by-wire" hydraulic circuit.

Of Furthermore, in the case of the electrohydraulic brake system, the first Section and the second section of the "brake-by-wire" hydraulic circuits, the associated with the braking devices of the front wheels a check valve be separated.

at a further embodiment of the electro-hydraulic brake system an output side of the first device can at least one electromagnetic actuated Proportional valve downstream, in the "brake-by-wire" operation as an inlet valve serves to the braking device with pressurized hydraulic fluid to be provided by the first institution becomes. Through the proportional valve, the hydraulic fluid pressure, with the brake device associated with the proportional valve be changed in terms of control.

if necessary can the braking devices of the rear wheels are electromechanically actuated.

In the case of the electrohydraulic brake system, the second device can have an actuatable by an actuating device, in particular by a brake pedal, brake cylinder which can be brought into fluid communication with a reservoir for hydraulic fluid. Furthermore, the brake cylinder, a tandem piston valve with a first pressure chamber and a second pressure chamber downstream, wherein the first pressure chamber and the second pressure chamber are each connected to electromagnetically actuated control valves. By providing a tandem piston valve with two pressure chambers, the brake valves upstream control valves can be supplied with hydraulic fluid from different pressure chambers, which in turn there an additional safety aspect hinieht offers that in case of leakage of a pressure chamber further hydraulic fluid pressure from the other pressure chamber via the corresponding control valve of the respective braking device can be supplied.

According to one preferred embodiment, the brake cylinder and this downstream tandem piston valve rigid, in particular via a Push rod, coupled together. This is a good power transmission from the foot-operated Master cylinder secured to the tandem piston valve.

Short description the drawings

The The invention will be described below with reference to the accompanying drawings explained in more detail. It demonstrate:

1 an electro-hydraulic brake system of the prior art;

2 a first embodiment of an electro-hydraulic brake system according to the invention;

3 a second embodiment of an electro-hydraulic brake system according to the invention;

4 a third embodiment of an electro-hydraulic brake system according to the invention; and

5 a fourth embodiment of an electro-hydraulic brake system according to the invention, similar to that in 3 illustrated embodiment.

preferred embodiments the invention

In the 2 to 5 Various embodiments of the electro-hydraulic brake system according to the invention are shown. In the 2 to 5 are such components as those in the 1 correspond, denoted by matching reference numerals. Furthermore, those components that are specifically on in the 2 to 5 illustrated embodiments, with continuous 300 . 400 respectively. 500 Numbered.

That in the 2 illustrated embodiment of an electro-hydraulic brake system 300 includes a brake pedal unit 201 in which a brake pedal 214 with a master cylinder 218 and a simulation piston 216 is operatively connected. A pedal sensor X measures the pedal position (kicked pedal travel) and the operating speed of the brake pedal 214 , However, it would also be conceivable that the pedal sensor X measures only the pedal position and the operating speed of an electronic control unit (in 2 not shown) or another device. A reservoir for hydraulic fluid or a brake fluid reservoir 220 represents the electro-hydraulic brake system 300 Hydraulic fluid available. The simulation piston 216 serves to give the driver the typical reaction behavior of the brake pedal of a conventional hydraulic brake system.

The brake cylinder 218 the in 2 illustrated embodiment is as a tandem cylinder with two pressure chambers 222 . 224 educated. Although in 2 a brake cylinder 218 with two equal pressure chambers 222 . 224 is shown, it is in principle also possible to use a tandem cylinder having different sized pressure chambers. For example, the radial cross section of the first pressure chamber 222 unlike the radial cross section of the second pressure chamber 224 be. This could be in the two pressure chambers 222 . 224 generated hydraulic pressure assume different values.

The first pressure chamber 222 is via a supply line 303a . 305a . 307a ' with the braking device 203 the left front wheel VL fluidly connected. At the point 310a is the supply line 303a . 305a . 307a ' with a turnoff 307a '' connected to the braking device 205 the right-hand wheel HR leads. Likewise, the second pressure chamber 224 via a supply line 303b . 305b . 307b ' with the braking device 207 the left-hand wheel HL fluidly connected. At the junction 310b leads from this supply line 303b . 305b . 307b ' a further direction 307b '' to the braking device 209 the right front wheel VR. The fluid circuits from the first pressure chamber 222 and from the second pressure chamber 224 to the corresponding braking devices 203 . 205 . 207 . 209 the vehicle wheels are at the in 2 illustrated embodiment formed symmetrically.

In the supply lines 303a . 305a . 307a ' / 307a '' and 303b . 305b . 307b ' / 307b '' are electromagnetically operated control valves 302a . 302b such as 306a . 306b . 306c . 306d arranged. At the in 2 illustrated embodiment, the control valves 302a . 302b as ISO valves and the control valves 306a . 306b . 306c . 306d designed as electrically actuated seat valves. The control valves 302a . 302b such as 306a . 306b . 306c . 306d are open when switched off.

In the hydraulic circuit of the left front wheel VL and the right rear wheel HR is located between the ISO valve 302a and the first pressure chamber 222 a first pressure sensor P1, and between the control valves 306a . 306b and the ISO valve 302a a second pressure sensor P2, while in the hydraulic circuit of the right front wheel VR and the left rear wheel HL between the ISO valve 302b and the control valves 306c . 306d a third pressure sensor P3 is provided. The first pressure sensor P1 measures the hydraulic pressure in the first pressure chamber 222 , Because both pressure chambers 222 . 224 may have the same radial cross-section, from the result of the pressure measurement of the pressure sensor P1 to that in the second pressure chamber 224 prevailing pressure to be closed.

Furthermore, the braking devices 203 . 205 . 207 . 209 each electrically operated control valves 308a . 308b . 308c . 308d downstream as exhaust valves. From the control valves 308a . 308b . 308c . 308d lead each derivatives 309a ' . 309a '' . 309b ' . 309b '' . 315 . 315b . 330 back to the reservoir 220 , For the control valves 308a . 308b and the control valves 308c . 308d is each a common derivative 315 . 315b provided at a branching point 320 be merged. From the branch point 320 performs only a single derivative 330 back to the reservoir 220 ,

Because the control valves 302a . 302b such as 306a . 306b . 306c . 306d are opened in the non-conducting state, when pressing the brake pedal 214 in "push-through" operation hydraulic fluid from the pressure chambers 222 . 224 via the corresponding supply lines 303a . 305a . 307a ' / 307a '' such as 303b . 305b . 307b ' / 307b '' under the same pressure the braking devices 203 . 205 . 207 . 209 supplied to the vehicle wheels. Unlike the in 1 shown brake system is thus in the in 2 described embodiment, a 4-wheel "push-through" operation possible.

In the 2 illustrated electro-hydraulic brake system 300 further comprises an energy unit 100 with a pressure accumulator 104 and an electric motor driven hydraulic pump 102 , The energy unit 100 is from the reservoir 220 via a supply line 330 , those of the above-mentioned derivation 330 corresponds to the reservoir, supplied with hydraulic fluid. The derivative of the from the hydraulic pump 102 act on pressure accumulator 104 flows into a hydraulic line 276 , in the electromagnetically actuated proportional valves 304a . 304b are arranged, which are closed in the non-conducting state. The output sides of the proportional valves 304a . 304b are each via the hydraulic fluid lines 311 . 311b with one of the pressure sensors P2, P3 and via the previously described supply lines 307a ' . 307a '' . 307b ' . 307b '' with the brake devices 203 . 205 . 207 . 209 the vehicle wheels connected. Another pressure sensor P4 monitors the hydraulic pressure in the accumulator 104 , Further, a check valve on the output side of the hydraulic pump 102 provided, the penetration of hydraulic fluid from the pressure accumulator 104 in the hydraulic pump 102 in the off state of the associated engine avoids. A pressure relief valve 105 that has a drive 106 is switched and is closed in the non-switching state, serves a safety-critical overpressure, for example, in the case of a defective pressure sensor P4, in the derivative 315 and from there via the hydraulic line 330 to the reservoir 220 drain.

Although in 2 not shown, are similar as in the 1 in the electro-hydraulic brake system of the present embodiment, an electronic control unit, corresponding temperature sensors, a power source in the form of a battery, etc. are provided.

The following is the operation of the in 2 shown electrohydraulic brake system first described in "push-through" operation. All control valves are located in the in 2 shown position, that is in a non-switching state, as he would be present for example in case of power failure.

The "push-through" operation by the brake pedal 214 generated hydraulic pressure in the brake cylinder 218 causes hydraulic fluid from the pressure chambers 222 and 224 displaced and through the ISO valves 302a . 302b and through the seat valves 306a . 306b . 306c . 306d in the supply lines 303a . 303b . 305a . 305b . 307a ' . 307a '' . 307b ' . 307b '' the braking devices 203 . 205 . 207 . 209 the vehicle wheels is supplied. Due to the pressure build-up in the supply lines 303a . 303b . 305a . 305b . 307a ' . 307a '' . 307b ' . 307b '' become the braking devices 203 . 205 . 207 . 209 acted upon by hydraulic fluid, which leads to the construction of a brake pressure and ultimately to the deceleration of the vehicle wheels. For releasing the brake pressure in the brake devices 203 . 205 . 207 . 209 in "push-through" mode the driver of the vehicle takes his foot off the brake pedal 214 , This allows hydraulic fluid from the supply lines 303a . 303b . 305a . 305b . 307a ' . 307a '' . 307b ' . 307b '' back to the two pressure chambers 222 . 224 of the brake cylinder 218 flow, causing the brake pressure in the brake devices 203 . 205 . 207 . 209 reduced.

In contrast to the "push-through" operation, the pressure build-up in the "brake-by-wire" mode of the electro-hydraulic brake system takes place by means of the pressure accumulator 104 , In this case, the open control valves in the non-switching state 302a . 302b from one in 2 Not shown control unit driven to this from the open position in to bring a closed position. In addition, the proportional valves 304a . 304b opened by the control of the control unit. Thus, in "brake-by-wire" operation hydraulic fluid from the accumulator 104 through the proportional valves 304a . 304b and through the corresponding supply lines 311 . 311b . 307a ' . 307a '' . 307b ' . 307b '' of which a part is also used in "push-through" operation, the braking devices 203 . 205 . 207 . 209 be supplied. By appropriate electronic control of the proportional valves 304a . 304b can the brake pressure in the individual braking devices 203 . 205 . 207 . 209 depending on the pedal travel X determined by the pedal travel and / or the operating speed of the brake pedal 214 be modulated. Furthermore, it is by appropriate control of the proportional valves 304a . 304b possible that the brake pressure in the supply lines to the left front wheel and right rear wheel is set differently to the brake pressure in the supply lines to the right front wheel and left rear wheel.

It sinks from the accumulator 104 provided hydraulic fluid pressure, which is measured by the pressure sensor P4, below a predetermined threshold, the hydraulic pump 102 operated to provide sufficient brake pressure in the brake devices 203 . 205 . 207 . 209 build. The hydraulic pump 102 is electronically controlled and started, whereby the hydraulic fluid reservoir 104 again with hydraulic fluid from the reservoir 220 is charged.

For releasing the brake pressure in the brake devices 203 . 205 . 207 . 209 become the control valves 306a . 306b . 306c . 306d closed and the control valves 308a . 308b . 308c . 308d open. The hydraulic fluid thus passes from the brake devices 203 . 205 . 207 . 209 about the derivatives 309a ' . 309a '' . 309b ' . 309b '' . 315 . 315b . 330 back to the reservoir 220 ,

With the in 2 shown electrohydraulic brake system is a so-called. 4-wheel "push-through" operation possible, in contrast to the in 1 The electrohydraulic brake system, in which only the two front wheels can be braked in "push-through" mode, represents a special aspect in terms of the braking performance of the 2 illustrated embodiment.

Of importance is in the in 2 illustrated electro-hydraulic brake system that the control valves 306a . 306b . 306c . 306d serve as intake valves to the braking devices both in the "push-through" and "brake-by-wire" operation. By assuming this dual function, the functionality is also without the proportional valves 238 . 240 . 244 . 246 of the 1 , which serve as inlet valves in "brake-by-wire" operation in the brake system shown there 1 omitted separating piston can be omitted.

Furthermore, the geometry of the hydraulic fluid lines, in particular allows the branch points 310a . 310b and the branch point 320 , a reduction in the number of control valves, reservoir lines, inlets and outlets. So are in the in 2 illustrated embodiment, two proportional valves 304a . 304b sufficient to control the hydraulic pressure in "brake-by-wire" operation compared to the four proportional valves 238 . 240 . 244 . 246 of the 1 ,

On Reason of the above-described specific aspects which, like the skilled person recognizes, as are not conclusive to be evaluated the production costs for the electrohydraulic invention Reduced brake system and reduced the total weight of the brake system. Of Further, due to the smaller number of components, the brake system be made more compact, which in particular when used in small Vehicles with low overall weight is advantageous.

Below are three other embodiments of a hydraulic brake system with respect to 3 to 5 described.

The in the 3 to 5 illustrated embodiments of the electro-hydraulic brake system include a reservoir for hydraulic fluid 220 that with a brake piston 218 connected in a fluid manner. Likewise is a simulation piston 216 provided to the driver upon actuation of the brake pedal 214 conveys the feeling of a conventional hydraulic brake system. As with the in 2 illustrated embodiment, a pedal sensor X is further provided. The two pressure chambers 222 . 224 of the brake cylinder 218 are in a fluid way with the reservoir 220 coupled, in addition, an electromagnetically actuated control valve 460 between the reservoir 220 and the first pressure chamber 222 is provided. Of importance for those in the 3 to 5 Illustrated embodiments is a brake cylinder 218 downstream valve piston 450 . 550 . 650 that with two pressure chambers 452 . 454 . 552 . 554 . 652 . 654 is trained.

The in the 3 and 5 illustrated brake system 400 . 600 also includes a sensor array 272 with several pressure sensors whose measured values can be compensated via temperature sensors T1, T2. The sensor group 272 is with an electronic control unit 212 connected. The control unit 212 is from a battery 210 With Energy supplied.

Referring to the 3 Both are pressure chambers 452 . 454 of the valve piston 450 in a fluid way with the reservoir 220 coupled for hydraulic fluid. Depending on the sensor group 272 the different will be in 3 shown electromagnetically actuated control valves 402a . 402b . 404a . 404b . 406a . 406b . 408a . 408b . 410a . 410b . 460 through the electronic control unit 212 driven. All control valves 402a . 402b . 404a . 404b . 406a . 406b . 408a . 408b . 410a . 410b . 460 are in the unconnected state in the in 3 shown position. On the electronic control should not be discussed in this context.

The first pressure chamber 452 of the valve piston 450 is via a supply line 412a , a control valve 402a and a hydraulic fluid line 418a with a braking device 203 connected to a front wheel. In front of the input side of the control valve 402a is a turnoff 422a provided, which the first pressure chamber 452 also via a control valve 408b and a hydraulic fluid line 420b with the braking device 209 a rear wheel connects. In an analogous manner, the second pressure chamber 454 of the separating piston valve 450 via a supply line 412b , a control valve 402b and a hydraulic fluid line 418b with the braking device 205 connected to another front wheel. Furthermore, there is a branch 422b the second pressure chamber 454 via a control valve 408a and a hydraulic fluid line 420a with the braking device 207 connected to another rear wheel.

It should be noted at this point that it would also be conceivable to use the control valves 402a . 402b each before the branch points 422a . 422b in the supply lines 412a . 412b to arrange. This would make operation of the brake system without the control valves 408a . 408b possible.

The input side of the hydraulic pump 102 receives via a hydraulic fluid line 430 and a filter unit 270 Hydraulic fluid from the reservoir 220 , Furthermore, a pressure accumulator 104 provided the braking devices 203 . 205 . 207 . 209 over the hydraulic fluid line 414a . 414b can act on pressurized hydraulic fluid. The braking devices 203 . 205 the pre-wheels are over the hydraulic fluid lines 418a . 418b each with check valves 406a . 406b connected. The check valves 406a . 406b in turn are each via hydraulic fluid lines 416a . 416b with the electromagnetically operated control valves 404a . 404b connected to the output side of the hydraulic pump 102 and the output side of the pressure accumulator 104 in a fluid manner via the hydraulic fluid line 414a are connected. Further, the brake devices 207 . 209 the rear wheels each via hydraulic fluid lines 420a . 420b with the electromagnetically operated control valves 410a . 410b and via the hydraulic fluid line 414b with the output side of the hydraulic pump 102 and the pressure accumulator 104 connected in a fluid way.

The functioning of in 3 shown electrohydraulic brake system will now be described first in the "push-through" operation, in which all the control valves in the in 3 shown position. In case of power failure 210 or in the event of possible malfunction of the electronic control unit 212 can via the operation of the brake pedal 214 the master cylinder 218 operated and consequently the rigidly coupled with this valve piston 450 be moved. Because the valve 460 is open in "push-through" operation, the hydraulic fluid from the two pressure chambers 222 . 224 during the displacement of the piston in the master cylinder 218 back to the reservoir 220 reach. The displacement of the piston in the master cylinder 218 is so on the valve piston 450 transfer. By displacement of the piston in the valve piston 450 in which its central valve 451 closed in a manner known to those skilled in the art, the hydraulic pressures in the first 452 and the second 454 Pressure chamber increases and hydraulic fluid is released respectively through the control valves 402a and 402b the braking devices 203 and 205 supplied to the front wheels. Because in the de-energized state, the control valves 402a . 402b Always open, the valve piston can 450 the braking devices 203 . 205 apply hydraulic fluid. In the same way, hydraulic fluid from the first pressure chamber 452 over the junction 422a and through the control valve 408b the braking device 209 fed. Analog hydraulic fluid passes from the second pressure chamber 454 over the junction 422b and through the control valve 408a to the braking device 207 , Also the control valves 408a . 408b are always open when de-energized. Thus, the "push-through" operation is possible even in the de-energized state of the entire electro-hydraulic brake system.

In brake-by-wire operation, the brake pressure is generated electronically 214 operated by the driver, the valve piston 450 does not move, because the valve 460 is closed and the hydraulic fluid from the pressure chamber 222 from the simulation piston 216 is guided, whereby the driver in the "brake-by-wire" operation, the conventional "brake feel" is mediated. In "brake-by-wire" operation, the pressure accumulator provides 104 pressurized hydraulic fluid is available. During a braking process, the control valves 404a . 404b as well as the valves 410a . 410b switched, that is, they move from a closed position to an open position. At the same time by the electronic control unit 212 the control valves 402a . 402b as well as the control valves 408a . 408b brought from the open position to the closed position. Thus, the hydraulic fluid from the accumulator 104 through the valves 404a . 404b the braking devices 203 . 205 the front wheels and through the control valves 410a . 410b the braking devices 207 . 209 the rear wheels are fed, whereby the vehicle is braked.

Should the pressure in the hydraulic accumulator present in "brake-by-wire" operation 104 no longer for one of the driver by pressing the brake pedal 214 initiated deceleration be ausrechend, so can via the electronic control unit 212 the engine of the hydraulic pump 102 be turned on. The hydraulic pump 102 acts on the accumulator 104 then with hydraulic fluid from the reservoir 220 over the supply line 430 ,

In "brake-by-wire" operation, the hydraulic pressure from the brake devices 203 . 205 . 207 . 209 drained as follows. It will be the control valves 402a . 402b brought from the closed position to the open position, whereby the hydraulic fluid from the brake devices 203 . 205 the front wheels back to the first and second pressure chamber 452 . 454 flows. The check valves 406a . 406b prevent the penetration of hydraulic fluid into the hydraulic fluid lines 416a . 416b , In addition, the control valves 408a . 408b opened and the control valves 410a . 410b closed. The hydraulic fluid thus passes out of the brake devices 207 . 209 the rear wheels each via the hydraulic fluid lines 412a . 412b back to the two pressure chambers 452 . 454 ,

Another embodiment of an electro-hydraulic brake system is in the 4 shown. At this point, only the differences to those in 3 illustrated embodiment received. In the 4 it can be seen that the braking devices 207 . 209 the rear wheels through the electronic control unit 512 be operated in an electromechanical manner. For this purpose, each of the two braking devices 207 . 209 comprise an electromotive actuator. The electronic control unit 512 receives control signals from the electronic control unit during a braking operation 212 depending on the pedal travel detected by the pedal sensor X and / or the operating speed of the brake pedal 214 , Furthermore, the electronic control unit receives 512 Measurement data from the speed sensors 507 . 509 , The electronic control unit 512 then determines the required braking deceleration of the rear wheels, which is then initiated by electromechanical means.

Another difference between the in 3 illustrated embodiment and those of 4 is that between the hydraulic accumulator 104 and the hydraulic pump 102 a check valve 540 is arranged. Thus, that of the hydraulic pressure accumulator 104 provided hydraulic fluid not back to the hydraulic pump 102 reach. However, the hydraulic pump can 102 , if necessary, the hydraulic pressure accumulator 104 with hydraulic fluid from the reservoir 220 apply.

In the 4 illustrated embodiment allows a 2-wheel "push-through" operation of the front wheels.The "brake-by-wire" operation of this electro-hydraulic brake system is carried out in an analogous manner to the in 3 illustrated embodiment. The pressure reduction in the brake devices 203 . 205 the front wheels are in "brake-by-wire" operation by opening the control valves 502a . 502b , by the hydraulic fluid from the braking devices 203 . 205 over the hydraulic fluid lines 512a . 512b back to the two pressure chambers 552 . 554 of the valve piston 550 and from there to the reservoir 220 can get. In "push-through" operation, the pressure is reduced immediately after releasing the brake pedal 214 because the control valves 402a . 402b already open. The hydraulic fluid is removed from the brake devices 203 . 205 in an analogous way as in "brake-by-wire" operation to the reservoir 220 recycled.

In the 5 illustrated embodiment of the electro-hydraulic brake system differs from the in 3 illustrated embodiment in that in this embodiment, the first pressure chamber 652 of the valve piston 650 over the hydraulic fluid line 612a that a branch 622a has, the control valves 602a . 602b and the hydraulic fluid lines 618a . 618b with the brake devices 203 . 205 the front wheels is connected while the second pressure chamber 654 of the valve piston 650 over the hydraulic fluid line 612b that a branch 622b has, the control valves 608a . 608b and the hydraulic fluid lines 620a . 620b in a fluid way with the brake devices 207 . 209 the rear wheels is connected.

As with the in 3 illustrated embodiment is a control valve 660 between the reservoir 220 and the master cylinder 218 arranged, which is open when de-energized. Furthermore, the master cylinder is 218 with the valve piston 650 rigid over a push rod 670 connected for optimum power transfer from the master cylinder 218 on the piston of the valve piston 650 to enable.

In "brake-by-wire" operation of the in 5 illustrated embodiment, the control valves 602a . 602b such as 608a . 608b brought from the open position to the closed position, while at the same time the control valves 604a . 604b such as 610a . 610b be brought from the closed position to the open position. The control of the control valves 602a . 602b . 608a . 608b . 604a . 604b . 610a . 610b happens through the electronic control unit 212 , Pressure reduction of brake pressure in brake devices 203 . 205 . 207 . 209 happens analogously to that of 3 shown embodiment.

A special aspect of the in the 3 to 5 shown embodiments is that the control valves 402a . 402b . 408a . 408b . 502a . 502b . 602a . 602b . 608a . 608b In push-through mode, they serve as intake valves, while they function as exhaust valves in push-through and brake-by-wire operation, using a single valve as an inlet and outlet valve an electro-hydraulic brake system must be present in order to ensure a functional "push-through" and "brake-by-wire" operation can be reduced.

Furthermore, in the in the 3 to 5 illustrated embodiments of the electro-hydraulic brake system requires less hydraulic fluid lines, a smaller number of proportional valves and no separating piston valves. This shows a comparison of the in the 3 to 5 illustrated electro-hydraulic brake systems and in 1 shown brake system. Due to the reduced number of components, the total weight of the electro-hydraulic brake system according to the invention is reduced. In a corresponding manner, the manufacturing costs are reduced. Furthermore, the electrohydraulic brake system according to the invention can be made more compact, which is particularly advantageous when installed in small vehicles with low weight.

The expert recognizes that in the 2 to 5 described embodiments are not limited to brake systems, in which the braking devices 203 . 205 for the front wheels and the braking devices 207 . 209 intended for the rear wheels. In other words, in all of the embodiments described herein, the reference numbers 203 . 205 . 207 . 209 be designated braking devices arbitrary braking devices of the front wheels or rear wheels.

Furthermore, the skilled artisan recognizes that in the in the 3 to 5 illustrated embodiments, pressure sensors are provided at corresponding locations, although these are not shown in the figures. The electronic control unit 212 may also receive control signals from other controllers, such as ABS, ASR, TC, FDR, BA, ART, Soft Stop and ESP.

Claims (20)

Electrohydraulic brake system ( 300 ) for motor vehicles, comprising: - a first device ( 100 ) for providing pressurized hydraulic fluid in a brake-by-wire operation and a second device ( 201 ) for providing pressurized hydraulic fluid in a "push-through" operation of the electro-hydraulic brake system ( 300 ); At least one braking device coupled to at least one vehicle wheel ( 203 . 205 . 207 . 209 ) with the first facility ( 100 ) and the second facility ( 201 ) can be brought into fluid communication, characterized in that an electromagnetically actuated control valve ( 306a . 306b . 306c . 306d ) of the braking device ( 203 . 205 . 207 . 209 ) is connected upstream, which serves both in the "push-through" and "brake-by-wire" operation as an inlet valve for applying the braking device ( 203 . 205 . 207 . 209 ) with hydraulic fluid. Electrohydraulic brake system according to claim 1, characterized in that the electromagnetically operable control valve is open in a circuitless state, electromagnetically actuated seat valve ( 306a . 306b . 306c . 306d ). Electrohydraulic brake system according to claim 1 or 2, with a "push-through" hydraulic fluid circuit ( 303a . 303b . 305a . 305b . 307a ' . 307a '' . 307b ' . 307b '' . 309a ' . 309a '' . 309b ' . 309b '' . 315 . 315b . 330 ) and a "brake-by-wire" hydraulic fluid circuit ( 276 . 311 . 311b . 307a ' . 307a '' . 307b ' . 307b '' . 309a ' . 309a '' . 309b ' . 309b '' . 315 . 315b . 330 ), characterized in that the "push-through" hydraulic fluid circuit of the "brake-by-wire" hydraulic fluid circuit by an electromagnetically actuated control valve ( 302a . 302b ) is disconnected. Electrohydraulic brake system according to claim 3, characterized in that the electromagnetically operable control valve is opened in a circuitless state valve ( 302a . 302b ). Electrohydraulic brake system according to one of the preceding claims, characterized in that an electromagnetically actuated control valve (closed in the non-switching state) ( 308a . 308b . 308c . 308d ) of the braking device ( 203 . 205 . 207 . 209 ) is downstream, which is used in the "brake-by-wire" operation as an exhaust valve for discharging hydraulic pressure from the Bremseinrich tions ( 203 . 205 . 207 . 209 ). Electrohydraulic brake system according to one of the preceding claims, characterized in that an output side of the first device ( 100 ) for the provision of pressurized hydraulic fluid in "brake-by-wire" operation with an electromagnetically actuated control valve closed in a non-switching state ( 304a . 304b ) connected is. Electrohydraulic brake system according to claim 6, characterized in that the electromagnetically operable control valve, an electromagnetically actuated proportional valve ( 304a . 304b ) is to controllably change the hydraulic pressure in the "brake-by-wire" operation. Electrohydraulic brake system according to one of the preceding claims, characterized in that in a vehicle with four wheels each vehicle wheel, a braking device ( 203 . 205 . 207 . 209 ), and that the electro-hydraulic brake system is designed for a 4-wheel "push-through" operation. Electrohydraulic brake system according to claim 8, characterized in that an output side of the second device ( 201 ) for providing pressurized hydraulic fluid in "push-through" operation with a braking device ( 203 . 205 ) of a front wheel and a rear wheel can be brought into fluid communication. Electrohydraulic brake system ( 400 ) for motor vehicles, comprising: - a first device ( 100 ) for providing pressurized hydraulic fluid in a brake-by-wire operation and a second device ( 201 ) for providing pressurized hydraulic fluid in a "push-through" operation of the electro-hydraulic brake system ( 400 . 500 . 600 ); At least one braking device coupled to at least one vehicle wheel ( 203 . 205 . 207 . 209 ) with the first facility ( 100 ) and the second facility ( 201 ) can be brought into fluid communication, characterized in that an electromagnetically actuated control valve ( 402a . 402b . 408a . 408b ) of the braking device ( 203 . 205 . 207 . 209 ) is connected upstream, which serves as an inlet valve in "push-through" operation for applying the braking device ( 203 . 205 . 207 . 209 ) with the second device ( 201 ) provided hydraulic fluid, and in the "push-through" and "brake-by-wire" operation as an exhaust valve is used for discharging hydraulic pressure from the braking device ( 203 . 205 . 207 . 209 ). Electrohydraulic brake system according to claim 10, characterized in that the electromagnetically operable control valve is open in a circuitless state, electromagnetically actuated proportional valve ( 402a . 402b . 408a . 408b ). Electrohydraulic brake system according to claim 10 or 11, characterized in that in a vehicle with four vehicle wheels, the electro-hydraulic brake system for the 4-wheel "push-through" operation is formed, and each braking device ( 203 . 205 . 207 . 209 ) an electromagnetically actuable control valve ( 402a . 402b . 408a . 408b ) is connected upstream. Electro-hydraulic brake system according to one of Claims 10 to 12, with one of the braking devices ( 203 . 205 ) associated "brake-by-wire" hydraulic circuit, one of the first device ( 100 ) comprehensive first section ( 430 . 414a . 416a . 416b . 414b . 420a . 420b ) and a braking device ( 203 . 205 ) second section ( 418a . 418b . 412a . 412b ), and characterized in that the first portion of the second portion by a check valve ( 406a . 406b ) is disconnected. Electrohydraulic brake system according to claim 13, characterized in that in a vehicle with four wheels each vehicle wheel, a braking device ( 203 . 205 . 207 . 209 ), and the first section and the second section of the respective brake-by-wire hydraulic circuits of the brake devices ( 203 . 205 ) of the front wheels through a check valve ( 406a . 406b ) is disconnected. Electrohydraulic brake system according to one of claims 10 to 14, characterized in that an output side of the first device ( 100 ) at least one electromagnetically operable proportional valve ( 404a . 404b . 410a . 410b ) is connected downstream, which serves in the "brake-by-wire" operation as an inlet valve for applying at least one braking device ( 203 . 205 . 207 . 209 ) from the first institution ( 100 ) provided pressurized hydraulic fluid. Electrohydraulic brake system according to claim 15, characterized in that in a vehicle with four wheels each vehicle wheel a braking device ( 203 . 205 . 207 . 209 ) and that the output side of the first device ( 100 ) two electromagnetically actuated proportional valves ( 404a . 404b . 410a . 410b ) for the braking devices ( 203 . 205 ) of the front wheels are connected downstream. Electrohydraulic brake system according to claim 16, characterized in that the braking devices of the rear wheels ( 207 . 209 ) are electromechanically actuated. Electro-hydraulic brake system according to one of Claims 10 to 17, characterized in that the second device ( 201 ) one by an actuating device, in particular by a brake pedal ( 214 ), actuatable brake cylinder ( 218 ) connected to a reservoir ( 220 ) can be brought into fluid communication for hydraulic fluid, and that the brake cylinder ( 218 ) a valve piston ( 450 ) with a first pressure chamber ( 452 ) and a second pressure chamber ( 454 ), wherein the first pressure chamber ( 452 ) and the second pressure chamber ( 454 ) each with an electromagnetically actuated control valve ( 402a . 402b ) connected is. Electrohydraulic brake system according to claim 18, characterized in that the brake cylinder ( 218 ) and this downstream valve piston ( 450 ) are rigidly coupled together. Electrohydraulic brake system according to claim 19, characterized in that the brake cylinder ( 218 ) with the downstream valve piston ( 450 ) via a push rod ( 470 ) connected is.